Once, during a barging holiday, two so-called friends of mine played a mean trick on me. They were making a delicious snack - fresh Shropshire strawberries dipped in melted chocolate. Yum. They passed one to me; I bit in, expecting my teeth to shatter the thin crust of chocolate before sinking into the succulent sweet pink flesh of the fruit, but ... Euuughhh! They'd done me a special one, with a pickled onion instead of a strawberry. They'd even stuck a strawberry stalk on to fool me. It was one of the most traumatic moments of my life. If those two are reading, I promise I haven't forgotten, and I promise I will get you back.

I had a similar experience watching Roger Cook's Greatest Hits (ITV1). No one was playing a trick on me this time, it was just my own fuddled brain. I know exactly who Roger Cook is - that fat bloke who used to get hit by criminals - but I'd somehow got it into my head that I was settling down to watch Peter Cook's Greatest Hits. I was all set for 1970s satire, Pete and Dud, a bit of The Secret Policeman's Ball, perhaps ... And, suddenly, here's that fat bloke getting hit by criminals. "Roger Cook, Yorkshire Television. I'd like to talk to you about money laundering." Biff! "Mr Yao ... or should I say Georgie Pie?" Pow! "Come and face the music, Dr Schubert." Bam!

The Cook Report ran for 13 years. Big Rog confronted - and generally got hit by - drug smugglers, arms dealers, people traffickers, loan sharks, ivory traders ... just about everyone operating on the wrong side of the law had a pop. For which he should be thanked. He's a proper investigative journalist, the like of which you don't see much any more. Bold and brave, he gets hold of a story in his teeth like a bulldog, and doesn't let go, exposing baddies and their wrong-doings.

But there was always something quite irritating about him - his sense of smug sanctimoniousness as he wielded his sword of justice, fighting a lone battle against the law-breakers. Well, huffing and puffing after them, anyway. Those confrontations - there was something toe-curlingly, buttock-clenchingly embarrassing about them. And not only did I end up feeling sorry for the money launderers / war criminals / black marketeers, but I actually ended up being on their side. Go on my son, have a go, hit the big fella with all the cameramen and boom operators running towards you!

In this programme he's revisiting some of his old cases, to see if the powers that be have done as he, Roger Cook, decreed they should. And no, in many cases they have not. The Costa del Sol has become more violent and more crooked. Lions are still being shot in Africa. And look what happened in America, and the rest of the world, after the authorities chose to ignore the warning signals that came out of Cook's investigation into airport security. Yes, 9/11, Afghanistan, Iraq ... If only we'd taken Roger Cook more seriously, none of it would have happened. Never mind that the investigation was into smuggling bombs on to planes, and there were no bombs involved in 9/11 ...

But it hasn't all been in vain. Here's Catherine, and her moving story. Catherine was kidnapped and forced to work as a prostitute until Sir Roger came galloping along on his white horse (the RSPCA might want to look into that) to rescue her. "If it hadn't been for you doing that programme," she says, "I'd have been gone."

Excuse me while I throw up. Oh, I'm sorry, Roger, for being so cynical. I think I'm still a bit cross with you for not being Peter Cook, and being a big chocolate-coated pickled onion instead.

Isn't Property Ladder (Channel 4) depressing? It's like the opposite of Grand Designs, which is about inspiring new buildings and interesting architecture. But this is about people wrecking nice old places - putting in ceiling lights, and en suite bathrooms, a bit of decking round the back - for one reason only: to make a profit. Today it's the turn of Steve in Nottinghamshire, who's got himself a lovely Methodist chapel. It's a beautiful, airy, high, light room with huge tall windows, as you'd expect in a chapel. So what does Steve do, he puts a floor in, cuts the place - and the windows - in half, turning the ground floor into a kind of dark cellar.

To be fair to Sarah Beeny, she does tell him not to, but stubborn Steve takes no notice. And he gets his profit, because someone else with no imagination thinks he's done good. But you wrecked it, Steve.